check whether two objects belongs to same class in C++

Question

How to check whether two objects belong to the same class in std c++ using templates or any function?

class A{};
class B{};

int main() 
{
    B b1, b2;
    A a1,a2;
    cout<< issame(a1,b1)<< endl;
    cout<< issame(a1,a2)<< endl;
}

Answer 1

C++ is statically typed, B and A are different types. Maybe its just a matter of your code not demonstrating the use case, but in your code there is no need to "check", you already know that B is not A. In a template the situation is different, you can have for example:

template <typename U, typename V>
void foo(U u, V v);

and then U and V can be either different types or the same. To check if they are the same you can use the type trait std::is_same_v<U,V>

Answer 2

You can define a function issame like

#include <type_traits>

//...

template<typename S, typename T>
constexpr bool issame(S, T) {
    return std::is_same<S, T>::value;
}

and use it just like in your example.

std::cout << issame(a1,b1) << std::endl;  // outputs "0"
std::cout << issame(a1,a2) << std::endl;  // outputs "1"